Project description:Industrial wine yeast strains possess specific abilities to ferment under stressing conditions and give a suitable aromatic outcome. Although the fermentations properties of Saccharomyces cervisiae wine yeasts are well documented little is known on the genetic basis underlying the fermentation traits. Besides, although strain differences in gene expression has been reported, their relationships with gene expression variations and fermentation phenotypic variations is unknown. To both identify the genetic basis of fermentation traits and get insight on their relationships with gene expression variations, we combined fermentation traits QTL mapping and expression profiling in a segregating population from a cross between a wine yeast derivative and a laboratory strain.
Project description:Natural grape-juice fermentations involve the sequential development of different yeast species which strongly influence the chemical and sensorial traits of the final product. In the present study,we aimed to examine the transcriptomic response of Saccharomyces cerevisiae to the presence of Hanseniaspora guilliermondii wine fermentation.
Project description:Industrial wine yeast strains possess specific abilities to ferment under stressing conditions and give a suitable aromatic outcome. Although the fermentations properties of Saccharomyces cervisiae wine yeasts are well documented little is known on the genetic basis underlying the fermentation traits. Besides, although strain differences in gene expression has been reported, their relationships with gene expression variations and fermentation phenotypic variations is unknown. To both identify the genetic basis of fermentation traits and get insight on their relationships with gene expression variations, we combined fermentation traits QTL mapping and expression profiling in a segregating population from a cross between a wine yeast derivative and a laboratory strain. 40 samples are analysed with 2 technical replicates, using a unique reference named pool of the 30 segregants. The transcriptome of each segregant is compared to the transcriptome of the pool. The transcriptome of 5 biologic replicates of each parental strain is also compared to this reference. An haploid derivative of the commercialized wine yeast EC1118 which sequence is available (Novo et al. 2009. PNAS, 106:16333-16338) called 59A was used as industrial wine yeast. It is a prototroph strain and has a MATa sexual type. The haploid laboratory strain S288C (MATa) was used for crossing.
Project description:In wine fermentation, the blending of non-Saccharomyces yeast with Saccharomyces cerevisiae to improve the complexity of wine has become common practice, but data regarding the impact on yeast physiology and on genetic and metabolic regulation remain limited. Here we describe a transcriptomic analysis of single species and mixed species fermentations.
Project description:We used genome-wide expression analyses to study the response of Saccharomyces cerevisiae to stress throughout a 15-day wine fermentation. Forty percent of the yeast genome significantly changed expression levels to mediate long-term adaptation to an environment in which ethanol is both a stressor and a carbon source. Within this set, we identify a group of 223 genes, designated as the Fermentation Stress Response (FSR), that are dramatically and permanently induced; FSR genes exhibited changes ranging from four-to eighty-fold. The FSR is novel; 62% of the genes involved have not been implicated in global stress responses and 28% of the genes have no functional annotation. Genes involved in respiratory metabolism and gluconeogenesis were expressed during fermentation despite the presence of high concentrations of glucose. Ethanol, rather than nutrient depletion, was responsible for entry of yeast cells into stationary phase. Ethanol seems to regulate yeast metabolism through hitherto undiscovered regulatory networks during wine fermentation. Keywords: time course, stress response, fermentation
Project description:The yeast Dekkera bruxellensis is as ethanol tolerant as Saccharomyces cerevisiae and may be found in bottled wine. It causes the spoilage of wine, beer, cider and soft drinks. In wines, the metabolic products responsible for spoilage by Dekkera bruxellensis are mainly volatile phenols. These chemical compounds are responsible for the taints described as ‘‘medicinal’’ in white wines (due to vinyl phenols) and as ‘‘leather’’, ‘‘horse sweat’’ and ‘‘stable’’ in red wines (due to ethyl phenols mainly 4-ethylphenol). Apart from the negative aroma nuances imparted by these yeasts, positive aromas such as ‘smoky’, ‘spicy’ and ‘toffee’ are also cited. Our goal was to identify the impact that the wine spoilage yeast Dekkera bruxellensis has on fermenting S. cerevisiae cells, especially on its gene expression level. To this end we co-inoculated both yeast species at the start of fermentation in a synthetic wine must, using S. cerevisiae-only fermentations without Dekkera bruxellensis as a control. All fermentations were employed in special membrane reactors (1.2 um pore size cut-off) physically separating Dekkera bruxellensis from wine yeast S. cerevisiae. Biomass separation with this membrane was done to abolish the possibility of hybridizing also D. bruxellensis probes on Agilent V2 (8x15K format) G4813 DNA microarrays designed just for S. cerevisiae ORF targets. The 1.2 um pore membrane separating both yeasts allowed the exchange of ethanol, metabolites and sugars during the fermentation.
Project description:Natural grape-juice fermentations involve the sequential development of different yeast species which strongly influence the chemical and sensorial traits of the final product. In the present study,we aimed to examine the transcriptomic response of Saccharomyces cerevisiae to the presence of Hanseniaspora guilliermondii wine fermentation. Paralell fermentations were carried out in natural grape-juice using S. cerevisiae for both single and mixed culture with a H. guilliermondii strain. For RNA extraction, cells were collected at 24h, 48h and 96 h from both fermentations
Project description:In order to asses yeast EC1118® strain expression changes during wine alcoholic fermentation triggered by various nutrient starvations, this experiment describes the gene expression under micronutrient starvations that lead to yeast cell death (oleic acid starvation, ergosterol starvation, pantothenic acid starvation and nicotinic starvation) or allow the maintenance of yeast viability (nitrogen starvation).
Project description:The yeast Dekkera bruxellensis is as ethanol tolerant as Saccharomyces cerevisiae and may be found in bottled wine. It causes the spoilage of wine, beer, cider and soft drinks. In wines, the metabolic products responsible for spoilage by Dekkera bruxellensis are mainly volatile phenols. These chemical compounds are responsible for the taints described as M-bM-^@M-^XM-bM-^@M-^XmedicinalM-bM-^@M-^YM-bM-^@M-^Y in white wines (due to vinyl phenols) and as M-bM-^@M-^XM-bM-^@M-^XleatherM-bM-^@M-^YM-bM-^@M-^Y, M-bM-^@M-^XM-bM-^@M-^Xhorse sweatM-bM-^@M-^YM-bM-^@M-^Y and M-bM-^@M-^XM-bM-^@M-^XstableM-bM-^@M-^YM-bM-^@M-^Y in red wines (due to ethyl phenols mainly 4-ethylphenol). Apart from the negative aroma nuances imparted by these yeasts, positive aromas such as M-bM-^@M-^XsmokyM-bM-^@M-^Y, M-bM-^@M-^XspicyM-bM-^@M-^Y and M-bM-^@M-^XtoffeeM-bM-^@M-^Y are also cited. Our goal was to identify the impact that the wine spoilage yeast Dekkera bruxellensis has on fermenting S. cerevisiae cells, especially on its gene expression level. To this end we co-inoculated both yeast species at the start of fermentation in a synthetic wine must, using S. cerevisiae-only fermentations without Dekkera bruxellensis as a control. All fermentations were employed in special membrane reactors (50 KDa pore size cut-off) physically separating Dekkera bruxellensis from wine yeast S. cerevisiae. Biomass separation with this membrane was done to abolish the possibility of hybridizing also D. bruxellensis probes on Agilent V2 (8x15K format) G4813 DNA microarrays designed just for S. cerevisiae ORF targets. The 50 KDa pore membrane separating both yeasts allowed the exchange of ethanol, metabolites and sugars during the fermentation. Fermentations were carried out in synthetic wine must in duplicate for both the control S. cerevisiae (strain Lalvin EC1118) and mixed fermentation. Sampling of yeast S. cerevisiae for RNA extractions were performed at 22 h of fermentation, during the exponential growth phase of S. cerevisiae, at 92 h and 144 h of fermentation, during its early and late stationary growth phase and at 187 h of fermentation, during its phase of growth decline.